This invention relates to a commutator placing machine, and particularly to a method and apparatus for accurately orienting a commutator and maintaining the orientation of that commutator as it is installed on an armature shaft.
A commutator is a device for connecting electrical current from a fixed set of brushes or contacts to the windings of a rotating armature. A commutator typically includes a plurality of evenly spaced conductive strips, usually copper, formed on a cylindrical base of insulating material. One end of each segment is formed into a tang, a hooked member around which the wire from the armature winding is placed to provide electrical contact.
As these strips rotate with the armature, different pairs are connected to the brushes, and the magnetic field set up by current passing through the winding connected to these contacts creates a force causing the armature to rotate. The angular position of the segments as they contact the brushes in relation to the angular position of their corresponding windings in the armature is precisely determined according to the type of motor into which the armature is placed. It is, therefore, essential that the commutator be placed on the armature with these segments accurately located with respect to their corresponding windings if the motor is to operate properly.
In a typical commutator placing machine, commutators are fed one at a time into a loading position. Armatures are also brought into position and properly aligned to receive the commutators. The commutators are oriented by some means and then installed on the armature shaft.
In a typical prior art machine, the angular position of the armature is set according to its designed characteristics. The commutator is first oriented to a fixed angular position and then installed onto the armature shaft. A typical machine would include a set of rails onto which the commutator is directed, and as the commutator started its movement down the rails toward the armature, the tangs on the commutator would become aligned with the rails. Actually, the spaces between the tangs receive the rails.
Occasionally, however, the commutators would not settle onto the rails accurately, and this would cause the commutator either to jam, become broken or be installed on the armature shaft in an inaccurate position. None of the prior art armature placing machines included any means for ensuring that the commutator orientation was correct before it was installed on the armature shaft and means for maintaining that orientation from the commutator loading position to its final seated position on the armature shaft.
It has been found that the opening in the commutator through which the armature shaft extends may not be properly formed or may include some irregularity which would tend to cause the commutator to rotate slightly as it approaches its final seating position on the shaft. Any rotation of the commutator will of course cause misalignment thereof and reduce the efficiency of that motor in which it is installed.